In this experiment we will create something that looks like a small volcano using equipment that can be found in any home or grocery store.
Equipment
2 cups preferably tall and narrow.
Vinegar
Spoon
Baking soda powder
Liquid soap or dishwashing liquid
Water
A drop of food coloring or gouache paint not required
Tray to do the experiment on to prevent mess not required
Experiment procedure
The procedure of the experiment can be seen in the following video.
Here is another video of the experiment with gouache colors filmed during the lockdown period.
Explanation
Vinegar with the chemical formula CH3COOH is an acidic substance. Baking soda NaHCO3 is a basic substance and together they create what is called an acid base reaction. Acid base reactions are chemical reactions in which a proton H plus passes from the acid to the base and they are characterized by very high speed. The chemical reaction that occurs is
CH3COOH aq + NaHCO3 aq CH3COONa aq + H2O l + CO2 g.
Aq means dissolved in water.
L means liquid state.
G means gas state.
In simple words the reaction tells us that vinegar and baking soda dissolved in water react with each other in a process that among other things releases carbon dioxide gas CO2.
The reaction as mentioned is very fast which means the gas is released very quickly and the whole solution erupts with gas at once.
When we add soap to the solution the released gas manages to foam it.
In a similar way you can blow with a straw into soapy water and see that a lot of foam comes out and it creates many small soap bubbles.
The food coloring has no essential role in the experiment and is used only to give color to the foam so it is not a required component.
For scientific accuracy it is important to note that the release of carbon dioxide gas is not a characteristic of acid base reactions but only of very specific acid base reactions between acids and two families of bases called carbonates and bicarbonates.
The carbonates are the source of the gas release in the reaction.
Interesting to note
You can use the experiment to make a real demonstration of a volcano.
Instead of a cup you can create or take a water resistant structure shaped like a volcano or build from cardboard clay or modeling clay a structure in the appropriate shape a cone with a hole at its top and place it around the cup.
Try also to change the amount of soap in the solution and see how it affects the speed of the process its thickness the size of the bubbles and more or change the amount of water and their temperature.
Also in a real volcano the molten rock lava that erupts from the mountain contains gases that foam it. You can see this by looking closely at tuff stone a stone that is ejected during a volcanic eruption. It is full of bubbles remains of gases that foamed it when it was still liquid.
By the way the same chemical reaction shown in this experiment can be used to inflate a balloon.
You can also make a similar volcano if you mix mentos candy with a carbonated drink.